When I was pregnant with my first son in 2007, I read that a boy in
the U.S. had a 1 in 91 chance of being diagnosed with an autism spectrum
disorder. A good friend was a special education teacher who attended
national meetings to keep up with the latest research. She told me she’d
noticed a definite increase in the number of autistic kids over the
course of her career (The odds today, as most of you already know, are
so much worse: 1 in 42 boys, 1 in 189 girls).
My friend said that nobody really knew what was causing the increase in
autism, but that the leading theory involved an upsurge of nerdy men
marrying nerdy women.

When my baby was born, I was smitten. He arrived ten days past his
estimated due date, weighed 7 pounds 1 ounce; he had peach fuzz on his
head and deep blue eyes. He was so sweet and adorable—and so helpless
and dependent on me to make wise choices for him.

A close relative, who had been stricken with polio as a boy, had died
of a neurodegenerative disease at age 69. Though he recovered from
polio, my family always suspected his later disease may have been caused
by his boyhood illness. So I went to my son’s 2-month well baby visit
glad that he would be getting DTaP and polio shots. I was surprised,
however, at how many other vaccines were recommended. I left the
doctor’s office feeling uneasy about injecting such a small baby with so
many bioactive substances at once.

I knew there had been a controversy surrounding vaccines and,
although I’d heard the link with autism had been thoroughly discredited,
I decided I needed to inform myself about the issue before I went back
to the doctor for my son’s 4-month visit. I earned my Ph.D. in
atmospheric science from Stanford University and had 18 years of
experience in scientific research when my son was born. I was very
interested in making an evidence-based decision on this issue.

That in November 1999 CDC data revealed that babies with the highest
early vaccine mercury exposure had a 7.6-fold increased risk of getting
autism compared to those with zero exposure. Instead of making this
information public, the CDC held an off-site meeting at the Simpsonwood
retreat and conference center with doctors and vaccine manufacturers to
decide how to manipulate the data to make these inconvenient results go
away.

I read David Kirby’s Evidence of Harm, subscribed to the SafeMinds newsletter,
and had a second baby in 2009. When my second son was 9 months old the
doctors were unhappy with his weight gain and diagnosed him with an
eating disorder. I grew disillusioned with standard medicine during the
stressful year that followed. We saw an eating therapist who told me to
distract my son into eating with zany behavior and a nutritionist who
gave me a list of junk foods to fatten him up. My little boy was also
subjected to a number of traumatic, often botched blood draws that
achieved little or nothing. It was I, with the help of a new, holistic
doctor, who finally improved my son’s appetite by giving him zinc and
other mineral supplements. With my second son’s eating problems I became
even more grateful to SafeMinds for giving me information about children’s health that wasn’t being covered in the mainstream media.

In 2011, when SafeMinds advertised for a volunteer with an
atmospheric science background, I sent them my resume and began a study
looking at geographical correlations between autism and atmospheric
mercury. Although I found a statistically significant correlation, I
eventually became skeptical of my own study. It didn’t really make
sense. The time trend in atmospheric mercury over the U.S. had been flat
since at least the mid 1990s and seemed inconsistent with the sharply
increasing trend I’d plotted in the autism data. In addition, the
diagnosed autism rate in China, the world’s biggest coal burner and
mercury emitter (and a country with horrendous air pollution), was lower
than in the U.S.

Around this same time, in 2012, Philip Landrigan and colleagues published an autism research strategy that included a list of the top 10 compounds suspected of causing autism.

Having studied and taught a survey course in environmental chemistry,
I recognized immediately that 3 of the first 5 compounds on their list
had been banned or sharply curtailed in the 1970s. But I had little idea
about the trends in some of the other compounds. So I decided to do a
study, based around Landrigan’s list, to answer 2 major questions:

1) What is the time trend in autism in the United States and how much
of the apparent rise is real rather than due simply to better
diagnosis?

2) How does that rise in autism, if it really exists, compare to the
time trends in each of the chemicals in Landrigan’s top 10 list?

Diagnosed autism prevalence has risen dramatically in the U.S over
the last several decades and continued to trend upward as of birth year
2005.

The increase in autism is mainly real, with only about 20-25 percent
attributable to increased autism awareness/diagnoses, and has occurred
mostly since the late 1980s.

In contrast to the upward trend in autism, children’s exposure to
most of the top 10 toxic compounds has remained flat or decreased over
this same time frame.

The environmental factors with time trends that correlate
positively to autism include 2 vaccine-related indices: cumulative
aluminum adjuvant exposure and cumulative total number of disease-doses
by 18 months; polybrominated diphenyl ethers (used as flame retardants);
the herbicide glyphosate (used on GM crops); and maternal obesity.

Figure 1. Autism prevalence vs. birth year
for California IDEA data, derived using two independent methods: 1)
Constant-age tracking of 9 year-olds over 20 years of annual reports
from 1991-2010 (red) and 2) Age-resolved snapshot from the most recent
report in 2010 (blue). The slope of each curve over the same birth year
interval, 1993-2001, is estimated with a least squares linear fit. The
snapshot fit (grey) spans ages 9-17 in the 2010 report. The constant-age
tracking fit spans report years 2002-2010. The snapshot:tracking slope
ratio over the 1993-2001 birth year interval is 0.80, suggesting that
80% of the tracked increase is real. (Reprinted from Environmental
Health 2014, 13:73 doi:10.1186/1476-069X-13-73) Note: due to
underascertainment among 5 and 6 year-olds, the age-resolved snapshot
curve decreases after birth year 2003. However, constant-age tracking
of 5 year-olds suggests that autism is still increasing in birth years
2004-2005.

Of course, correlation does not mean causation, so this last
point should be interpreted with caution. It also should not be taken as
a comprehensive list. There are many other environmental factors I
would have liked to have included in my paper, but was not able to
reconstruct their trends, including prenatal ultrasound,
the use of acetaminophen (Tylenol), and antibiotics. Trends in key
nutrient levels like vitamin D, zinc, and magnesium may also be
important.

The vaccine index correlations, on their own, would mean little, but
become more significant when you consider that thousands of parents are
reporting autistic regression in their children following severe adverse
reactions to vaccines. The severe, obvious reactions are the exception,
not the rule, among autistic kids, but these cases are real and have
been conceded and compensated under U.S. law.

With children’s well-being at stake, we should be leaving no stone
unturned until we get to the bottom of these parental reports. Instead,
we have dismissed them with statistics and called it Science, despite
knowing that in some cases those statistics were deliberately manipulated.

It’s also not enough for epidemiologists to show that most kids can
tolerate the current vaccine schedule without developing autism. That’s
already obvious, but it doesn’t prove there’s not a vulnerable subset of
children who can’t.

The director of the NIEHS recently described air pollution as a probable “real agent involved in the increasing prevalence
of ASD.” Her comments were based on the multiple epidemiological
studies that have found correlations between autism and air pollution.
I’ve read those studies and have been surprised that none has recognized
that air quality has been improving in the U.S. over recent decades,
beginning with the 1970 Clean Air Act.Can we logically expect that further reductions in air pollution will reverse the upward trend in autism?

We owe it to our children to exert ourselves to what John F. Kennedy
once described as the “discomfort of thought” and to consider the whole
body of scientific evidence.

It’s time to stop resting on what JFK called the comfort of myths.

Myth #1: We are not failing to protect children
against autism, rather, autism has been there all along and we’re just
succeeding in diagnosing it better.

Myth #2: We can account for the upward autism trend
with comfortable explanations like air pollution, which nobody likes, or
with “throw-up-our-hands-and-do-nothing” explanations based on a vague
convergence of multiple toxins.

Because of the “convergence of many toxins” paradigm, the mainstream
scientific community has led parents to believe that we cannot know what
causes autism and therefore we cannot prevent it. It’s hard to dismiss
this paradigm. The many chemicals in our environment at best are not
helping our kids and certainly are contributing to their overall body
burden of toxins. But we also should be skeptical of these kinds of
vague explanations. If they were true, would autism have such a distinct time trend,
with an inflection point in the late 1980s? Especially considering that
many of the worst toxins were in decline at that point? Also, despite
hand-waving arguments to the contrary, there is no evidence that autism
existed prior to the 1930s.

The “we can’t know” attitude also absolves scientists and doctors of
responsibility for prevention, and suggests the only thing we can do is
diagnose autism as early as possible in order to do behavioral
intervention.

The unfortunate truth is that the environmental influences causing
autism may at the same time be medically useful, even lifesaving. Rather
than the current approach of blanket denial, wouldn’t it be better to
confront the situation honestly and come up with solutions that promote a
more optimal health outcome for children as a whole?

Parents deserve better and more honest information about how to
protect their children, not only from autism, but also from the other
chronic conditions that afflict so many kids these days: asthma, ADHD,
and severe food allergies, many of which, like autism, are fundamentally
disorders of the immune system.

Some members of the environmental health community once showed true
courage in taking on powerful industries, like the lead industry, that
were poisoning children’s brains

We need such leaders again to challenge the illogic of past and
current explanations for the rise in autism, from nerdy parents to air
pollution, to end the denial of inconvenient truths, and to act to
protect innocent children.

Cynthia
Nevison, Ph.D., is a research scientist at the University of Colorado
at Boulder. Her work focuses on atmospheric and environmental science.